Question

If in a coil rate of change of area is $\frac{5metr{e}^2}{millisecond}$ and current become 1 amp form 2 amp in $2\times {10}^{-3}$ sec. If magnetic field is 1 Tesla then self inductance of the coil is

• A. 2 H
• B. 5 H
• C. 20 H
• D. 10 H

Answer 1

The correct option is D 10 H

$e=B.\frac{dA}{dt}=L\frac{di}{dt}\Rightarrow 1\times \frac{5}{{10}^{-3}}=L\times \frac{(2-1)}{2\times {10}^{-3}}\Rightarrow L=10H$